Machines such as dozers, loaders, excavators, backhoes, motor graders, and other types of heavy equipment typically include stationary and moving parts, and one or more hydraulic actuators to accomplish a variety of tasks. Sealing members are often provided between two or more of the stationary and moving parts in order to retain fluids that provide lubrication, cooling, and/or a hydraulic pressure source for the hydraulic actuators. These sealing members may be exposed to high pressures and/or temperatures, which may lead to deterioration, and eventual failure of the sealing members. Failure of a sealing member resulting from exposure to pressures and/or temperatures in excess of predetermined thresholds may result in damage to components of the machine and considerable down time for the machine while damaged components are repaired or replaced.
One example of a sealing arrangement used in machines such as the machines described above may include press-in-place (PIP) seals provided as cylinder head gaskets and/or cylinder liner sealing arrangements. A cylinder head gasket is typically provided between the cylinder block and the cylinder head. The cylinder head gasket may be in the form of one continuous element, or in the form of several elements. Ring-shaped seals may also be provided to conform approximately to the outer dimensions of each of the respective cylinder liners provided around each cylinder in the cylinder block. The cylinder liner ring seals prevent coolant from weeping upwards through the metal press fit between each cylinder liner and the cylinder block, and also prevent combustion gases or excess gases from a natural gas intake manifold, for example, from mixing with the coolant.
Another example of a sealing arrangement found in machines may include axial face seals that are used to seal two relatively rotating bodies against each other. These face seals keep dirt and other contamination from reaching sensitive parts of a machine, such as bearings, and retain fluids within fluid-filled housings. Face seals may include two highly polished metal rings facing each other and rotating relative to each other. Each of the face seals may be respectively supported by resilient elastomeric rings that can be compressed in order to prevent fluids from leaking around the face seals, and to allow the face seals to align with each other. In all of the various sealing arrangements, the elastomeric sealing members must be able to withstand high temperatures and pressures for extended periods of time without deterioration.
A problem with conventional sealing arrangements is that the sealing members are typically completely encased between mating parts of the machine, and are not readily observable in order to determine whether they are still in good condition. Generally, a failure of a sealing member is only discovered after fluids begin to leak out from between parts of the machine, fluid pressures required for proper operation of the machine drop, or there is a catastrophic failure of one or more parts of the machine. A decrease in the structural integrity of a sealing member, or a catastrophic failure of the seal may result in one or more parts of the machine no longer receiving proper lubrication or cooling. Damage to the parts may result, requiring the replacement of the parts and down time for the machine.
One attempt to provide a visible indicator when a rubber product has been exposed to a temperature that may be detrimental to the product's performance or safety is disclosed in U.S. Pat. No. 7,278,369 to Kelley et al. (“the '369 patent”). The '369 patent provides a temperature indicator for a rubber article comprising a thermochromic material, wherein the rubber article is selected from the group consisting of tires, belts and hoses. A thermochromic material is compounded with an elastomeric compound to form an elastomeric temperature indicator. The thermochromic material changes color at a predetermined temperature, thereby providing a visual indicator that the temperature has risen to a level likely to cause permanent damage to the rubber article.
Although the temperature indicator of the '369 patent provides a temperature indicator for tires, belts and hoses, it does not provide a way for visually monitoring whether a sealing member positioned between two machine parts has exceeded a predetermined threshold temperature or pressure.
The disclosed sealing member is directed to overcoming one or more of the problems set forth above and/or other problems of the prior art.